Rinse the brown and wild rice; pour into a 2-quart casserole dish. To the rice add red bell pepper, green bell pepper, zucchini, carrot and celery. Stir in garlic powder, onion powder, vegetable bouillon and margarine. Mix well, pour water over mixture, and cover.
Bake in preheated oven for 30 minutes; check at this point to see if more water needs to be added. Bake for to 30 to 50 minutes more, or until rice is cooked. Stir well before serving and season with salt and pepper.